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I/O Rule Analysis Report

The following example shows an I/O Rule analysis report:

Full Analysis                 SUPPLY (VAX-11/780)                       Page   3 
PA Vx.x
Saturday 01-OCT-2006 00:00 to 23:59
CONCLUSION 3.{I0060}
Swapping  or  modified  page  writing  is  creating  an excessive load on the noted disk.  This may be a
memory related problem, however if the swapping file is  on  a shared  system  disk,  the situation can
be improved by moving it to a less utilized disk.
Total number of samples supporting this conclusion:  4
CONDITIONS
1. 	ANY_DISK_OVER_QL_THRESHOLD .EQ. 1.00 
2. 	PERCENT_CPU_TIME_IN_FILE_SYSTEM .LT. 30.00 
3. 	EXEC .LT. 35.00 
4. 	DISK_SWAPPING_IO_RATE ( DISK_OVER_QL_THRESHOLD_X ).GT. DISK_IO_RATE ( DISK_OVER_QL_THRESHOLD_X ) / 
.00 

5. 	OCCURRENCES .GE. 4
EVIDENCE
Volume w/Highest Queue Length         %tim %tim 
--------------------------------------------  file EXEC 
Name        IOs/sec Pag.IOs/sec Swp.IOs/sec  sys. mode Time of occurrence 
------------ ------- ----------- -----------  ---- ---- ------------------ 
   1               2         3          4        5    6              7     
BRANDY1           34         5         20       10   10     1-OCT 09:04:00 
BRANDY1           29         3         23        8    9     1-OCT 09:06:00 
BRANDY1           31         5         22        3    3     1-OCT 09:08:00 
BRANDY1           32         4         27       11    0     1-OCT 09:10:00

The following statements are keyed to the columns in the previous I/O Rule Analysis report:

1. Name of the volume on which excessive swapping occurred. This volume had the highest queue length during the interval exampled.
2. Average number of I/Os per second to the volume from the node currently being analyzed (SUPPLY).
3. Number of paging I/Os per second to the volume. The value of paging I/Os per second is a subset of the total I/Os per second as described above.
4. Number of swapping I/Os per second to the volume. This value is also a subset of the total I/Os per second.
5. Percentage of CPU time spent in the file system.
6. Percentage of CPU time spent in executive mode.
7. Beginning time of the interval in which the condition occurred.

In the previous example I/O Rule Analysis report, the disk queue length on volume BRANDY1 exceeded its threshold on four occasions during the reporting interval. In each occurrence, less than 30 percent of the CPU time was spent in the file system and less than 20 percent of the CPU time was spent in executive mode. Swapping I/Os per second have values of 20, 23, 22, and 27, thereby contributing to more than 50 percent of the total operations to volume BRANDY1.